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PostPosted: Wed Aug 27, 2008 9:56 pm 
Hello-

I am a new member here, and have been follwing this site for a few months; I must say, it is very informative!~!

Anyway, I wanted to know if you plan to review the Sigma 150 500 OS lens; you were dead on with Sigma 120 400 OS on your review, and were right re: focusing issues and sharpness-

I was wondering if you will be reviewing the Sigma 150 500 OS?


Thaks-

kevin


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PostPosted: Wed Aug 27, 2008 10:09 pm 
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Location: Germany
Hello Kevin, and welcome to the friendly Camera Labs forum!
Well, no! I personally have no intention to review said lens. Why?
- the 150-500 is larger and heavier than the 120-400
- from Sigma's own MTF-figures it should be no better in sharpness than the 120-400mm
- OS should give the same (disappointing) results
- it costs 150-200€ more than its shorter cousin
:( :( :(

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Thomas (beware: Nikon-fanboy and moderator!) My Lens Reviews, My Pictures, My Photography Blog
D800+assorted lenses


Last edited by Thomas on Thu Aug 28, 2008 2:04 pm, edited 1 time in total.

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PostPosted: Thu Aug 28, 2008 12:18 am 
Well Thomas-

I had originally had purchased a Sigma 120 400 OS the same week you had reviewed it, and coudn't agree more with your review of the lens.

However, I still was looking for more reach, and purchased a Sigma 150 500 OS. I was surprised that it took sharper and clearer pics with my Nikon D300 that the Sigma 120 400 OS, and I didn't have to focus at f8 to get clear sharp shots.

The reason I was asking is that I thought your techniques of reviewing lenses was excellent, and wanted to see if the larger Sigma 150 500 OS was proven under your methodolgy of testing was a better lens. Or if not, then maybe I had gotten a quality lens up to 400mm.

Regards,

Kevin


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PostPosted: Thu Aug 28, 2008 7:17 am 
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That's an interesting observation, Kevin!
Can you show us some pictures?
How does the OS work?

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Thomas (beware: Nikon-fanboy and moderator!) My Lens Reviews, My Pictures, My Photography Blog
D800+assorted lenses


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PostPosted: Tue Sep 02, 2008 10:46 am 
I got my 150-500OS around 2 weeks before Thomas’ test of the 120-400OS. I must admit that IMAO it’s a very fine 150-400mm lens and a good 400-500mm lens. I wanted to post my results but I had some really crazy results using my Kenko PRO-300 1.4x DG teleconverter in the 400-500mm area. The teleconverter on another lens (Tamron) lens gave a very tiny IQ decrease (previous Kenko products give a large IQ decrease) that made me happy. But when I used the teleconverter on the 150-500OS then it gave me surprisingly much BETTER results in the 400-500mm area!?! Personally I’m very sceptical about this so I did not post anything about it, yet I chose to keep the lens … nothing wrong in having a unexplainable good IQ :D The OS maybe have some of the same problems that you experienced … not as bad though … and don’t forget the OS works with a teleconverter – AF does not! I have just reorganized my photo archives and are taking a backup of it … so I can post some shots … but it have to wait a little.


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PostPosted: Wed Sep 03, 2008 5:00 pm 
Okay, I will start by testing the stop capability of the OS. I find that it is hard to give a totally fair review of an Image Stabilization System (ISS) simply because the performance depends just as much on the ISS as on the users’ performance. So in the end any test can only give a directional guess on the quality of an ISS. This explains why I will use the calculated (absolute) Tv_max reference instead of a relative one found by my skills without the use of the ISS. I will not make a statistical evaluation of my shots since that too will be heavily influenced my skills (unofficially I had 50% more success with 1/40 sec than 1/80 sec). So instead I will make a list of Tv and do some 5 to 10 shots for each. Then at each Tv I see if it is possible to get an image that does not show clear signs of shaking … and that’s my test passed criteria. It is obvious that I took all the pictures while standing and with NO kind of support. I have not made any improvements in order to enhance the IQ, but I do use my own picture style in order to get a correct looking picture (compared to the standard setting the contrast is set to -2 and the saturation is set to +1).

Equations that I will use:
It is the rule of thumb that the maximum shutter speed is: Tv_max = 1/(FL in 35mm). I use an EOS 450D so: Tv_max = 1/(FL * 1.6). At 500mm TV_max is 1/800 sec and using the 1.4x teleconverter (700mm) it is 1/1120 sec. I won’t argue for this but I calculate the gained stops (stop_gain) from the maximum possible Tv_max using the OS (Tv_max_os) by using the equation: 2^(stop_gain) = Tv_max/Tv_max_os <=> stop_gain = ln(Tv_max/Tv_max_os)/ln(2).

The OS-test for 500mm:
I took pictures of an air conditioner placed some 15m away. I took shots at Tv = 1/160, 1/80, 1/40, 1/30, 1/20 sec. I focused using AF and the aperture was set to F6.3.

Two 100% crops from a 1/160 shot:
Image Image
At the left picture one can see that under the screw (tried to make it my focus point) there is a label. The label is below a plastic membrane that seems to cause some diffusion due to the internal reflections. This is -obviously- most viewable around the red parts of the label, and especially around the thinnest red parts. It gets even more viewable even if the F-number is raised. So one should only look at the black label parts and the screw to investigate if the image contains signs of shake. I do know that the character of the label makes it impossible to tell much about the IQ, sadly I don’t have time to find or setup something better here and now.
The letters on the right picture say: RN-F 5G15 (the R look a lot like an A due to the font). This part of the picture is found at the bottom edge and is not really in focus but it is again possible to see that the image does not shake.

Two 100% crops from a 1/80 shot:
Image Image
Both the left and the right picture show no clear signs of shaking.

Two 100% crops from a 1/40 shot:
Image Image
Both the left and the right picture show no clear signs of shaking.

Two 100% crops from a 1/30 shot using F9:
Image Image
Both the left and the right picture show no clear signs of shaking. The IQ is better than in the 1/40 shot.

Two 100% crops from a 1/20 shot:
Image Image
Clearly the 1/20 shots are no good at 100% crop, so I would say that Tv_max_os at 500mm is: 1/30 (maybe 1/25 – I did not have time to test that), so the gained stops are: ln(800/30)/ln(2) = 4.74. Would it then be unfair to call it a 4 to 5 stop OS?



The OS-test for 700mm:
Again, I took pictures of an air conditioner placed some 15m away. I took shots at Tv = 1/125, 1/100, 1/80, 1/60, 1/50 sec. The aperture was set to F9. I could not focus using the AF due to the teleconveter so I had to move a little forward and backward or adjust the focus on the lens.

Two 100% crops from a 1/125 shot:
Image Image
Both the left and the right picture show no clear signs of shaking.

Two 100% crops from a 1/100 shot:
Image Image
Both the left and the right picture show no clear signs of shaking.

Two 100% crops from a 1/80 shot:
Image Image
Both the left and the right picture show no clear signs of shaking.

Two 100% crops from a 1/60 shot:
Image Image
Both the left and the right picture show no clear signs of shaking, But the IQ is very bad. Looking at the full image one can see that the DOF is in fact very tiny so I tried to increase the F-number to F16 at the next shot.

Two 100% crops from a 1/50 shot (F16):
Image Image
Both the left and the right picture show no clear signs of shaking, and the picture is much sharper than the 1/60 one, so I conclude that at such high FL it is necessary to get enough DOF.

I did not have time to test if I could go below 1/50 sec, so I just say that Tv_max_os at 700mm is: 1/50, so the gained stops are: ln(1120/50)/ln(2) = 4.49.

I think it is worth remembering that Gordon too made a test of a Sigma lens, the 50-500EX lens, http://www.cameralabs.com/forum/viewtopic.php?t=2900. According to the test the Olympus ISS gave: ln(1000/30)/ln(2) = 5.06 stops. Yet we are looking at 100% crops so the pixel resolution also counts. The E-510 has got 10.0MP and the EOS 450D got 12.2MP. So the pixel resolution of E-510 is sqrt(12.2/10)x smaller, and inserting this gives: stop_gain = ln(1000/(30* sqrt(12.2/10)))/ln(2) = 4.92. Including the fact that I did not really go to the limit I would say that the two ISS performs pretty equivalent. Gordon talks about a slow AF – not a problem with my lens … well it’s below some 0.25sec most of the time … don’t know if it is faster or I’m just more easy to satisfy.

Well I didn’t really have time to perform an IQ test, so I will just show a 100% crop of an older image taken with 700mm, F9, 1/320 sec, and no post processing:
Image
Now this is just a crop but if you go and see the hole image, http://img99.imageshack.us/my.php?image=test02yc4.jpg, you see a lot of fine dust particles within the DOF … clearly the 150-500OS + kenko 1.4x teleconverter is not the worst performing lens combination in the world.


Conclusion: IMAO the Sigma OS and the Olympus build-in ISS performs quite similar. The Sigma 150-500OS and the Sigma 50-500EX should also give a quite similar IQ. So all in all I think the Sigma 150-500OS lens is good … especially for the price paid!


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PostPosted: Sun Sep 07, 2008 12:04 pm 
Well I must admit that I bought the Sigma 150-500OS lens because I wanted to take better photos at my cottage. I have just been up there to do the garden work … and for the first time with the lens. So now I have not just tested the lens – I have used it at the things I intended to use it at! During my garden work I saw countless types of dragonflies and butterflies. I saw frogs, toads and strange large insects I have never seen before. So when I could allow myself a break I naturally rushed to try the lens out. But most of the animals where gone and I did not have much time to take a break … typical :/ Well anyway I still saw some animals that I could get some shots of, like this Red Admiral butterfly:
Image
As one can clearly see from the image the butterfly is eating from an apple. The settings of the photo where: AF: auto, FL: 500mm, Tv: 1/160, F11, OS = 1. Yet what does this photo look like at 100% crop? Well the truth is that the photo above IS the 100% crop … and the full photo is found here: http://img300.imageshack.us/img300/1217/butterflysw4.jpg. Now I only took handheld shots, some 200+ (Tv: 1/125, 1/160 or 1/200), so not all my shots where good. I did some ruff statistics on how many bad ones there where and I found that 1/3 where bad: in 50% of the cases it was caused by me, wrong settings, in 25% it was cased by bad DOF and in the last 25% it was OS related issues.
I also took some images in very poor light conditions like these two toads:
Image
The settings of the photo where: AF: auto, FL: 500mm, Tv: 1/125, F6.3, OS = 1. Again the photo looks great although it’s a 100% crop, the full photo can be found here: http://img218.imageshack.us/img218/1427/frogon0.jpg. So I could use the highest aperture at 500mm without compromising with the IQ!

I have to say that I’m pleased with the IQ performance of this lens and that the sharpness is so good that it could probably benefit from a better camera house like the 15MP 50D … I have also used ISO 400 most of the time so a good ISO performance really could make the lens look a lot better!


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PostPosted: Mon Sep 15, 2008 7:24 pm 
I will just try to summon things up in a conclusion … I will start out by giving my answers to Thomas’ 4 points:

A) the 150-500 is larger and heavier than the 120-400
- Well in all respect, I’m am quite far from being the most masculine man on earth and carrying it around on and around my cottage, some 2 acres, didn’t make me tired.

B) from Sigma's own MTF-figures it should be no better in sharpness than the 120-400mm
- I don’t think the lens has got a sharpness issue. Even my 12MP EOS 450D camera can’t force it to its limit at 500mm. The lens is supposed to be sharper than the 50-500EX even if it’s not called an EX lens … Sigma now uses the EX term for lenses with a fixed largest aperture.

C) OS should give the same (disappointing) results
- I guess my result were better ;) Furthermore the OS should according to Sigma be a 4 stop solution, so I think you had a bad copy … I had often heard that the Sigma quality control is not known to be good!

D) it costs 150-200€ more than its shorter cousin
As I have said earlier I think the lens I got did gives me a great value for the money, so I won’t complain about the price. It’s kind of strange because in a way in most of the tests I have seen the Sigma 120-400OS is called a very soft and/or bad lens … so cousins can be very different … or maybe it’s the quality control issue (QC) … it is really hard to tell :?

Now knowing that the Sigma 150-500OS is a budget long-telezoom lens, I did fear that it could have some problems with pincushion distortion. But judging from the images I have taken pincushion distortion is very hard to find! The OS performance lives up to my expectations, the sharpness as well as the speed (aperture performance) are way better than what I expected and the colours are good. The AF is fast enough for me, but I did have some problems with front and back focusing at 500mm … yet with some training it seems that I have taught the AF to do things right ;)
I have taken a look at the 150-500OS reviews on: FM. It seems to confirm that others had got their hands on Sigma 150-500OS lenses with similar qualities as mine. Yet a lot of other people got their hands on a bad copy … so the QC is an issue regarding this lens.
So summoning everything together: If you need a long-telezoom lens and are willing to take the risk of having to return a lens or two … or maybe tree … then this lens is a great tool and a good value for the money.


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PostPosted: Mon Sep 29, 2008 2:54 pm 
Your wanted review is now almost done :0)
You can find it here: Sigma 150-500mm OS review
You may like it or you might not, my style of reviewing is not exactly
a science style review, it's more like a review of a practical user :0)


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